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Floods, leaks, and plumbing issues can lead to serious water damage and mold growth and should be handled by a professional ASAP. But what about creeping, recurrent mold issues that come back year after year? How do you fight mold when you don’t have leaks and floods?

Unless your home is a pharmaceutical research laboratory “clean room,” chances are you have mold somewhere. Mold spores are ubiquitous in the natural environment and a few can be found on just about every square inch of every building. These dormant, nearly indestructible spores are in the air we breathe and are generally harmless in low concentrations. But given the right conditions (like winter moisture), they can grow like gangbusters and cause serious health and safety issues. So how do you fight back?

1. Admit you have a problem

In cases where major plumbing issues, leaks, and flood damage can be ruled out, a mold problem is very likely an indoor moisture problem. Just sleeping and exhaling in your bedroom raises the relative humidity of the space. After all, humans are more than 60 percent water by body weight. Add to that figure some of your favorite activities (showering, boiling pasta, raising tropical fish) and indoor humidity can quickly get out of control. This is no big deal if you can manage to get your living quarters dry again, but all too often we lock our homes up tight and that moisture sticks around.

2. Get psychro

Indoor moisture is often expressed as “relative humidity.” Relative humidity is the percentage of moisture in the air, relative to how much moisture the air can hold at its current temperature. Engineers use a psychrometric chart to help illustrate this idea, showing that warm air can hold more water than cold air. Whenever air holds too much water, some of it will condense (turn into liquid) when it touches a cold surface (think of droplets on a cold glass of water).

In your home, the cold surfaces tend to be the exterior walls and windows. Water that condenses onto these surfaces may not dry (especially if you have furniture and curtains right next to them). And mold loves moisture.

3. Blow off some steam

The key to arresting the moisture (and slowing down condensation and mold growth) is to regularly and thoroughly ventilate your space. Open the windows and crank the fans. It may only take 5 minutes to get a complete air change.

4. What else can you do?

If you live in a home with recurring mold problems, a holistic approach may help. Ventilate and use heat to keep relative humidity between 30 and 50 percent. Routinely wipe up condensation when you see it on windows and windowsills. Keep furniture away from exterior walls to allow airflow. Use ventilation fans and ensure they’re working. And check that your dryer vent is connected and unblocked.

If these steps aren’t enough or if you live in an excessively humid climate, you may have to strategically use a dehumidifier (watch out: these use a lot of electricity, so don’t run them during peak energy times). Or you might look into upgrading your windows and insulation. In some homes, a crawl space vapor barrier may also help lower indoor humidity.

If mold does develop, clean minor mold growth with a soap and water solution and don’t let it get out of hand. For areas covering more than 10 square feet, the Environmental Protection Agency recommends hiring a contractor or other professional service provider to remediate the space.

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about Rebecca

Rebecca is a freelance copywriter and editor living in the SF Bay Area with her husband and two kids. She enjoys productively channeling her anxiety into safety-minded articles for home and garden, running with her robot trainer, and advocating on behalf of the Oxford comma.